crooked lake plot study 2011

Potential for Native Aquatic Plant Growth after Control of Eurasian Watermilfoil

2011 Crooked Lake Plot Study

James A. Johnson, M.S.

Lake Scientist

Freshwater Scientific Services, LLC

2011 Crooked Lake Plot Study2011 Crooked Lake Plot Study

James A. Johnson, M.S.

Lake Scientist

Freshwater Scientific Services, LLC

LakeUse

WaterQuality

PollutionFromLand

AquaticPlants

NutrientsFish

2011 Plot Study

• Establish 6 study plots (early June)

• Remove Eurasian milfoil from plots

• Assess aquatic plant growth (late Aug)

Questions• What native plants will grow?

Questions3. Will the abundance and diversity of

native plants be sufficient to protect water clarity and provide fish habitat?

Questions3. Will these native plants slow the

reestablishment of Eurasian milfoil?

Average Water Depth

0

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80

1 2 3 4 5 6

Plot

De

pth

(in

ch

es

)

1. Water Depth

2. Types of plants

3. Plant Height

4. % Coverage

Results• What types of plants

Results• What types of plants

Coontail

Results• What types of plants

Coontail

Muskgrass

Results• What types of plants

Coontail

Muskgrass

Illinois Pondweed

Results• What types of plants

Coontail

Muskgrass

Illinois Pondweed

Sago Pondweed

Results• What types of plants

Coontail

Muskgrass

Illinois Pondweed

Sago Pondweed

Bushy Pondweed

Results2. How common was each type of plant?

- % Occurrence

4 ÷ 9 = 44%

Results - % Occurrence

Eurasian Watermilfoil

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1 2 3 4 5 6Plot

% O

cc

urr

en

ce

Coontail

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% O

cc

urr

en

ce

Muskgrass

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% O

cc

urr

en

ce

Illinois Pondweed

0%

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% O

cc

urr

en

ce

Sago Pondweed

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1 2 3 4 5 6

Plot%

Oc

cu

rre

nc

e

Bushy Pondweed

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% O

cc

urr

en

ce

Eurasian Watermilfoil

0%

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1 2 3 4 5 6Plot

% O

cc

urr

en

ce

Results2. How densely did each type of plant

grow?

% Cover

Plant Height

Water Depth

Biovolume

Results - % Cover

Eurasian Watermilfoil

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Ave

rag

e %

Co

ve

r

Coontail

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Plot

Avera

ge %

Co

ver

Muskgrass

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Plot

Averag

e %

Co

ver

Sago Pondweed

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100

1 2 3 4 5 6

Plot

Av

era

ge

% C

ov

er

Illinois Pondweed

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1 2 3 4 5 6

Plot

Av

era

ge

% C

ov

er

Bushy Pondweed

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Plot

Ave

rag

e %

Co

ve

r

Eurasian Watermilfoil

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Av

era

ge

% C

ov

er

Results - Plant Height

Eurasian Watermilfoil

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1 2 3 4 5 6

Plot

De

pth

/Pla

nt

He

igh

t (i

nch

es)

Coontail

0

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80

1 2 3 4 5 6

Plot

De

pth

/Pla

nt

He

igh

t (i

nch

es)

Muskgrass

0

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40

50

60

70

80

1 2 3 4 5 6

Plot

De

pth

/Pla

nt

Heig

ht

(in

ch

es)

Sago Pondweed

0

10

20

30

40

50

60

70

80

1 2 3 4 5 6

Plot

De

pth

/Pla

nt

He

igh

t (i

nch

es)

Illinois Pondweed

0

10

20

30

40

50

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70

80

1 2 3 4 5 6

Plot

De

pth

/Pla

nt

He

igh

t (i

nch

es)

Bushy Pondweed

0

10

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60

70

80

1 2 3 4 5 6

Plot

Dep

th/P

lan

t H

eig

ht

(inch

es)

Results - % Biovolume

Eurasian Watermilfoil

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6Plot

% o

f W

ate

r V

olu

me

Coontail

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f W

ate

r V

olu

me

Muskgrass

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f W

ate

r V

olu

me

Illinois Pondweed

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f W

ate

r V

olu

me

Sago Pondweed

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f W

ate

r V

olu

me

Bushy Pondweed

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f W

ate

r V

olu

me

Coontail

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f Wat

er V

olum

e

Muskgrass

0%

20%

40%

60%

80%

100%

1 2 3 4 5 6

Plot

% o

f W

ater

Vo

lum

e

Summary of Findings• Treatments reduced milfoil

• Regrowth of milfoil fragments in untreated plots

• Coontail and Muskgrass dominant- dense, persistent “carpet”

• Taller plant species also fairly common - should provide quality habitat for fish

• Natural recruitment likely

Full Report Available for Download at…